This invention relates to a process for preparing stable opaque clouds in fluids, employing partially debranched starch as a clouding agent. This invention also relates to such an agent and to a process for preparing it.
As used herein, the term "opacity" refers to the amount of light transmittance of solutions or dispersions. As the solution or dispersion becomes cloudy, the opacity increases and the amount of light transmittance decreases.
In the art of clouding fluids, especially in an attempt to achieve the desired opacity or cloud inherent in natural juices, it is known and standard practice to form oil-in-water emulsions using edible oils. In bottled beverages the cloud typically has been provided by citrus oils for citrus flavored beverages, or by neutral vegetable oils (e.g. coconut oil) for non-citrus flavored beverages. This cloud may be enhanced by the presence of weighting oils in the beverage. In dry beverage mixes the cloud has been provided by incorporating spray-dried emulsions containing plastic fats, such as hydrogenated coconut oil, cocoa butter (U.S. Pat. No. 4,529,606) or triglycerides (U.S. Pat. Nos. 4,705,691 and 4,790,998), or hydrogenated coconut oil, inorganic pigments such as titanium dioxide, and hydrocolloids such as gum Arabic (U.S. Pat. No. 3,658,522). Similar emulsions have been used in liquid beverage systems (U.S. Pat. No. 4,479,971).
A major drawback in the use of these clouds is the development of an undesirable soapy flavor which is due to oxidative rancidity and hydrolysis of the oil and fat. This problem is compounded because the soapy off-flavor develops during storage and may not be discovered until the product is sold. Development of this off-flavor in bottled and canned beverages may be due to factors such as heat and/or sunlight. In dry beverage mixes development of the off-flavor may be due to various factors, such as incomplete fixing of the fat initially, release of the fat during processing (due to the mechanical force and/or heat developed during ribbon blending), or adverse storage conditions (i.e., high heat and humidity). The presence of the fat leads to further problems such as clumping of the mix and insolubility of the mix when reconstituted in water. The use of antioxidants to overcome the off-flavor problem is undesirable and often limited by government regulations. Hence, oil- and fat-free clouding agents have been explored.
Stable oil- and fat-free dry clouds have been described. One is a fat-free cloud prepared by co-drying an aqueous dispersion containing a major amount of a solubilized malto dextrin and a minor amount of xanthan gum and titanium dioxide (U.S. Pat. No. 4,187,326). Another involves the combination of a non-diary base and a new orange flavor emulsion to provide the cloud ("Breakfast Orange Drink Scores Formulation Breakthrough", Processed Prepared Food, June 1980, p. 116). The non-diary base is a component of the stabilizer, which also contains pectin, carboxymethyl cellulose, xanthan gum and carrageenan gum. Typically non-dairy bases are stabilized dried emulsions containing 20 to 50% oil or fat.
Beverage cloud systems also have been prepared from protein-stabilized fat emulsions (U.S. Pat. No. 4,790,998) and starch dispersions (U.S. Pat. No. 4,349,577). Other starch-containing (U.S. Pat. No. 4,619,833) and pectin-containing (U.S. Pat. No. 4,529,613) beverage clouds have been reported.
It is an object of this invention to provide a simple oil- and fat-free cloud and precloud which may be used in any fluids, especially in beverages and beverage mixes.
The use of starch as a fat-free clouding agent has met with less than optimal results due to the tendency of dilute starch dispersions to retrograde upon storage. The starch cloud is unstable because as the starch retrogrades, it tends to precipitate out of the fluid dispersion.
Starch is a polysaccharide typically comprising a mixture of about 20-25% amylose and about 75-80% amylopectin which is organized into compact granular structures. Amylose is a linear polymer of D-anhydroglucose units which are linked by alpha-1,4-D-glucosidic bonds. Amylopectin is a large branched polymer of amylose chains linked by alpha-1,6-D-glucosidic bonds in a tree-like structure. Depending upon the variety of plant from which the starch is obtained, amylose ordinarily contains between 250 and 12,500 D-anhydroglucose units and amylopectin contains between 400,000 and 3,125,000 D-anhydroglucose units.
Enzymes, or mixtures of enzymes which saccharify and debranch starch, have been used in starch conversion processes for the commercial production of low molecular weight oligosaccharides and sugars, such as dextrose (glucose). Starch conversion is the degradation of starch to lower molecular weight components by treatment with acid, oxidizing agents, heat, alkali or alpha-amylase enzymes. Enzymatic conversion of starch typically involves preferential hydrolysis of the alpha-1,4-D-glucosidic bonds by amylase, and only limited, if any, hydrolysis of the alpha-1,6-D-glucosidic bonds.
In the enzymatic conversion of starch to thin-boiling (low viscosity) starch, hydrolysis of branched fragments may be incomplete. For sugar production, however, complete conversion of starch to sugar is desirable, and debranching enzymes have been used to degrade the branched alpha-limit dextrins (branched starch fragments which resist further hydrolysis by alpha-amylase) which remain intact after the enzymatic hydrolysis of alpha-1,4-D-glucosidic bonds. Glucoamylase, an enzyme which liquifies and saccharifies starch, has been employed for this purpose. Glucoamylase rapidly hydrolyzes alpha-1,4-D-glucosidic bonds and slowly hydrolyzes alpha-1,6-D-glucosidic bonds, releasing glucose. A debranching enzyme, such as pullulanase or isoamylase, which rapidly hydrolyzes only the alpha-1,6-D-glucosidic bonds, releasing short chain amylose, has been suggested for use in conjunction with glucoamylase and alpha-amylase to improve the efficiency of production of high dextrose syrups. These syrups are starting materials in the manufacture of crystalline dextrose and high fructose corn syrup. See Maize, Recent Progress in Chemistry and Technology, pp. 157-179, Academic Press, Inc. (1982); and Slominska, L., et al., Starch/Starke, 11: 386-390 (1985).
Additionally, debranching enzymes (enzymes which release short chain amylose from starch) have been proposed for use in low calorie alcoholic beverage production to improve fermentability of branched starch fragments; in production of maltose from starch in conjunction with beta-amylase; in low DE maltodextrin (30-55 glucose units) production to induce proteins to aggregate in aqueous emulsions; and in enzymatic conversion of starch into a soluble syrup having a high quantity of disaccharides and trisaccharides. These debranching enzyme applications are directed to problems arising from the presence of branched starch or dextrin fragments following starch conversion processes. In each application, the debranching enzyme is employed in the complete conversion of starch to a variety of low molecular weight fragments such as sugars or maltodextrins. The thickening, adhesion and gelling characteristics of starch are lost.
The use of debranching enzymes to fully debranch starch, with hydrolysis of substantially all alpha-1,6-D-glucosidic bonds, so as to obtain pure, or amylopectin-free, low molecular weight amylose is taught in U.S. Pat. No. 3,730,840 to Sugimoto, et al; U.S. Pat. No. 3,881,991 to Kurimoto, et al; and U.S. Pat. No. 3,879,212 to Yoshida. These patents do not teach the conversion of starch to sugars and other soluble fragments. The object of these patents is to produce pure short chain amylose. The presence of any residual amylopectin is taught to be objectionable.
The background of enzyme-related starch technology does not suggest that useful starch compositions may be prepared by employing debranching enzymes to partially debranch the amylopectin component of the starch, yielding a mixture of short chain amylose, amylopectin and partially debranched amylopectin, with or without substantial conversion of the starch. The functional properties of the partially debranched starch of this invention are novel. Furthermore, nothing in the literature suggests the utility of an enzymatic process for partially debranching starch as a replacement, in whole, or in part, for oil- and fat-containing clouds which may be used in fluid dispersions. The enzymatic process offers significant advantages over other starch modification processes, particularly in food and cosmetic applications where the demand for "natural" products persists.